We are currently studying the growth and decline of hippocampus-dependent abilities (largely memory) in both humans and in mice. At this point we already have established that in both species there is a marked rise in hippocampus-dependent behavior during childhood, a stabilization in young adulthood, and a considerable decline in old age. Many important age points are still missing, of course, and we are not yet ready to establish any parallels. In humans the age curves for two different memory tests differ markedly. Verbal coding memory increases linearly over a long period (2 to 21) whereas "image memory" develops very suddenly between the ages of 4.5 to 5.5. Image memory also declines considerably more dramatically in old age, and this finding casts considerable doubt on the idea of a "benign" memory loss in middle age. We have so far studied mouse memory in terms of how long the animal remembers one thing (modified spontaneous alternation test) but are about to begin studying how many things can be remembered. We expect mouse memory to parallel human image memory. So far mouse memory jumps suddenly at 3-4 weeks of age and shows a great decline between the ages of about 7 and 12 months.